fix(redis): treat stale-fd KeyError as a connection error (#2592)

* fix(redis): treat stale-fd KeyError as a connection error

* Add regression test: KeyError is a redis transport connection error

* style: blank line between test methods

* Remove file committed to the wrong path

* style: blank line between test methods

* Fix tuple closing in connection_errors

* Resolve Transport at module level in the regression test

* Update t/unit/transport/test_redis.py

---------

Co-authored-by: Asif Saif Uddin {"Auvi":"অভি"} <auvipy@gmail.com>

Author: kokhlo

kombu/transport/redis.py

@@ -173,7 +173,13 @@ def get_redis_error_classes():
             exceptions.ConnectionError,
             exceptions.BusyLoadingError,
             exceptions.AuthenticationError,
-            exceptions.TimeoutError)),
+            exceptions.TimeoutError,
+            # A stale fd can still fire on_readable for a channel that was
+            # already dropped after a broker restart (#2582): the poller
+            # guard from #2561 makes the common path a debug log, but any
+            # KeyError that still escapes must be treated as a connection
+            # error so the consumer reconnects instead of dying.
+            KeyError)),
         (virtual.Transport.channel_errors + (
             DataError,
             exceptions.InvalidResponse,

t/unit/transport/test_redis.py

@@ -2921,6 +2921,10 @@ def test_handle_event(self):
 
         p.handle_event(13, ~(redis.READ | redis.ERR))
 
+    def test_connection_errors_include_keyerror(self):
+        errors = redis.Transport.connection_errors
+        assert KeyError in errors
+
     def test_on_readable_ignores_unmapped_fd(self):
         p = self.Poller()
         assert 35 not in p._fd_to_chan